Propane deasphalting of crude residua of hydrocarbon oil



Patented Feb. 16, 1954 PROPANE DEASPHALTING OF CRUDE RESIDUA OF HYDROCARBON OIL John G. Ditman,

Foster Wheeler Flushing, N. Y., assignor to Corporation,

New York, N. Y.,

a corporation of New York Application December 21, 1950, Serial No. 201,982 3 Claims. (01. 19614.46)

This invention relates to separation of asphalt from crude residua in the refining of hydrocarbon oils and more particularly to the propane deasphalting of said crude residua.

In propane deasphalting processes commonly used in refining of petroleum for the separation of asphalt from crude residua, difficulty is encountered due to foaming in stills used to recover propane from deasphalted oil and asphalt products particularly when the stills are operating at relatively low temperatures and using steam as the source of heat. Various processes for suppressing foam have been used, one of which processes involves spraying propane into the top of a tower used as a still. The foam, in this process, is broken by the liquid spray. A disadvantage of this said one process is that the quantity and temperature of the injected liquid is critical. For example, should an excessive quantity of liquid be sprayed into the tower, the temperature thereof may be depressed excessively by the evaporation of the liquid propane thus aggravating the foaming condition. In a second known process, coils or tubes carrying high pressure steam are disposed in the upper part of a tower operating as a still to superheat the vapor thus breaking the foam. This second process has not been entirely successful in that it is not possible to include sufficient heating surface, namely, coils or tubes, to provide the necessary superheat required.

In the present invention, feed comprising a mixture of propane deasphalted oil and propane is heated to a temperature at which a substantial portion of the propane is evaporated. The liquid and vapor mixture is then passed into a distilling tower in which the vaporized propane flows upwardly, while the liquid passes downwardly into a catch-pan and thence is conducted into a heater where the temperature thereof is raised to a degree substantially higher than that to which the feed is heated in the first-mentioned heater and at which degree more of the propane is vaporized. The mixture of vaporized propane and deasphalted oil so heated is thereafter returned to the lower part of the column wherein the vapor passes upwardly while the deasphalted oil passes downwardly and is conducted to a stripper. A portion of the hot deasphalted oil from the bottom of the tower is recirculated to the upper part thereof where it is projected downwardly in a spray and into intimate contact with the aforesaid rising vapors. Since the recirculated oil is at a higher temperature than the rising vapors, eflicient heating of the vapors by direct heat exchange relationship will result. At the same time, the spray affords mechanical breaking of the foam. Propane vapors are thereafter removed from the top of the tower and passed to a condenser.

The invention will be understood from the following description when considered in connection with the accompanying drawing in which the single figure shows diagrammatically and partly in section suitable apparatus for performing the process of the invention in one embodiment thereof.

Referring to the drawing, feed which comprises a mixture of deasphalted oil and propane, is passed through a conduit Ill to a low pressure steam heater ll wherein the mixture is heated to a degree at which a substantial portion of the propane in the mixture is evaporated under the prevailing pressure. The temperature to which the mixture would normally be heated would be 220 F. After heating, the mixture of vapor and liquid from heater ll flows through conduit i2 into distilling tower [3 at an intermediate point of said tower and below a baiile it which extends transversely of the tower and has a vapor passage 5 therein which passage communicates with an upper chamber It in the tower. A catch-pan i1 is positioned within the tower below baflie H but in spaced relationship with the bottom IB of the tower thereby dividing said tower into an intermediate chamber l9 and a. lower chamber 20. Catch-pan 17 has a riser passage 2| in the central portion thereof which extends upwardly into intermediate chamber I! of the tower, said riser having a deflector 22 positioned thereover which deflects gases flowing upwardly through the riser from chamber 20 into said intermediate chamber Hi.

The liquid passing downwardly through intermediate chamber I!) from conduit I2 is caught by catch-pan IT and flows therefrom through pipe 23 into a high pressure steam heater 24. In the heater 24, the liquid is heated to a degree substantially higher than that to which the mixture is heated in heater I I so that more of the propane therein is vaporized. The degree to which the mixture is heated would normally be approximately 320 F. The mixture of vapor and liquid from heater 24 is passed into the lower chamber 20 of tower l3 through conduit 25 which communicates with the tower below catch-pan l'l. Vapors entering the tower through conduit 25 pass upwardly through riser passage 2| and thence are deflected into intermediate chamber I9 of the tower thereafter to pass upwardly with anflunsenr ar vapor from pipe l2 through passage IS in baflic ll whence the vapors enter upper chamber it of the tower.

The hot deasphalted oil flows downwardly from conduit into the bottom ill or the tower and is withdrawn therefrom through an outlet conduit 26,- ,seiddeasphalted oil. thereafter being assed at a steam stripper wherein the final traces of propane will be removed therefrom.

A portion of the deasphalted oil flowing throughconduit 26 is recirculated by a recirculation pump 21, which has its suction incommumoatlonthrough a pipe 28 with conduit 28 and'has its discharge in communicatiomwimi a spray 30, through the conduit 29 whlchisprayameisdnznpe per chamber it of tower i3 and above baflie Mi Spray 30 directs hot dealspba ted .oil, which oil is at approximately 320"- F. downwardly and into intimate, direct heat exchange relationship.

with the rising vapors 'in upper chamber l6 of tower i3. As shown, the, hot dcasphalted oil is passed into a bubble tray 31 in. chamber iii which trail hasriserslfl with caps 33 thereonand a downspout Hi The hot oil flows onto tray 3! and gases, which pass into chamber l6 through passage 15, ,flowthrough risers 32 and are directed downwardly andinto intimate .contact with the oil onsaid-tray by caps 33. After said gas has thusly passedein contactuwith the oil=on the tray, saidoil flows downwardly through downspout 34 onto bafiie 1L As the rising vapors are at a temperature of approximately 2209-230" F and the reoirculatedchot deasphaltedwoil is at approximately-32% E emcient heating of the vapors; by; intimate and ,direct. heat exchange relationship results: At thesame timepthe spray oi, hot oil fromspray 30;- snows-mechanical breaking of foam. The superheated, propane vapors ppssfrom: upper chamberl6 r through conduit 35am! are conductedxtora. condenser. not shown.

Any lfoam, therefore; which forms in tower i6 is supppessedsby thesuperhoatlng pf the propane vapors passing-in co tact witlr thersprayoihot oil and also bywtherbreaking of said .ioam by the spray of hot non-evaporatins, .liquid.

It will be apparentithat various .modifications maybe-m de mine Iornrof theapparatus herein disciosedandsinvthesteps of themetnod herein deseriued without departing; from: the spirit =of the dnzention which vis-rnot to be limited except.- ing ,by 'the scopeiofsthe appendedolaima What .is claimed As:

1. In the propane deasphalting ,ofi crude hydro carbon oil residua having, asphalt therein, the processor recosering :propane from a lictuidrmixtrue of propaneldeasphalted. oil and propane and suppressing fclannals;encouintcred.v in said proces whichnomprisesheating saidtmixture .in a heating, zone to substantially 220 F. at. which .temperature a portion of the propane therein is vaporized, passingsva-nor andheatedrliquid from theheatingizone into, a distill'inshzone flowing liauid .irom the. distilling zone .to another heatinggzonewhereinsaid liquidis heatedto sun stantialls' 320 F. at tharpiiopanee in the .liquid is, vaporized. L flowing residue liquidland vapor, fromsaid other heating zone into. a..lower...part oi the. distilling, zone, superheatin isaid aporin the di' tillinaz ne'by email-neg apportion at :said. torsiibstantially 320 F. into contact and, direct heat exchange relationship; with said vapor in ,OLJZHBI distillinsgzone to cause which temperature more of residue liquid heated ;;which comprises suppression of foaming in the latter, and withdrawing vapor from the distilling zone after said vapor has passed in heat exchange relationship with the residue liquid.

2. In the propane deasphalting of crude hydrocarbon oil residua having asphalt therein, the pnocesswofrecovering propane-aroma vliquid mixture of propane deasphalted oil anfiipropane and suppressing foaming encountered in said process heating said mixture in a heating zone to substantially 220 F. at which temperature: a: portion of the propane therein is vaporized, passing vapor and heated liquid from the heating ,zens into an intermediate zone of art elongatedrsubstantially vertically extending distillingizone haning an upper zone, an intermediate zoneand a lower zone, the lower zone and'intermediate zone being in communication withxonesanother so that vapor will rise therefrom and pass into said zone, flowing liquid from the intermediate zone of said distilling,- zone to another heating zone wherein saidnliiquidnis heated to substantially 320 F. at which temperature more of the propane in the liquid is vaporized, flowing residue liquid and ,vapor from said other heating zone into the lower zone of the distilling zone, superheating said vapor in the distilling zone by spraying a portion toisaid residueliquidirom said lower zone into contact and-direct heat exchange relationship with the vapor in the upper zone tocause suppression of foaming, in the distilling, zone, andrwithdrawing vapor 'fronisaid upper zoneof the. distillingzonfl afterrsaid. vapor, haspassed in heat exchange relationship, with saidresidue from the other heating zone.

3.- In the propane deasphaltingof crude-hydrocarbon oilqresicluar having asphalt therein, the process of recovering propane from a liquidmixtureoii propane deasphalted oil and propane and suppressing ,foaming. encounteredin said process whichcomprisestheating said mixture in a low pressurersteamheating zone to substantially220" F.- at which-temperature a portion of the propane therein is. vaporized, passing vapor andfheated liquid fromthe w pressure steam heating zone into anintermediate zone of .an elongated substantiallyvertioally extendingdistilling zone having an upper zone, anintermediatezone and a lowenzone the lower zone. and intermediate zone being in communication with one another so that vapor; will rrise therefrom and, pass into said uppvza'zoner flowingrliauidirom the intermediate zoneoi said distilling .zone..to a high pressure steamzheatingzone wherein said liquid is heated toosubstantially, 320 F. at which temperature more .of rthewpropane in the liquid is vaporized, flowing: residue liquid and yapor from said high pnessure steamhesting zone into the lower zone of-..said vdistilling.zone, superheating the vapor in the distillingzone by, spraying a portion, of said residue liquid into contact and :direct heat exchange relationship with the vapor in the upper zoneto cause suppression of fo'aminginthe distilling ,zone, and withdrawing from theupper zone of said distilling zone the superheatedfiapor.

JOHN Gl DITMAN;

References Citedin the file of this patent UNITERSTAFI'ES PATENTS 

1. IN THE PROPANE DEASPHALTING OF CRUDE HYDROCARBON OIL RESIDUA HAVING ASPHALT THEREIN, THE PROCESS OF RECOVERING PROPANE FROM A LIQUID MIXTURE OF PROPANE DEASPHALTED OIL AND PROPANE AND SUPPRESSING FOAMING ENCOUNTERED IN SAID PROCESS WHICH COMPRISES HEATING SAID MIXTURE IN A HEATING ZONE TO SUBSTANTIALLY 220* F. AT WHICH TEMPERATURE A PORTION OF THE PROPANE THEREIN IS VAPORIZED, PASSING VAPOR AND HEATED LIQUID FROM THE HEATING ZONE INTO A DISTILLING ZONE, FLOWING LIQUID FROM THE DISTILLING ZONE TO ANOTHER HEATING ZONE WHEREIN SAID LIQUID IS HEATED TO SUBSTANTIALLY 320* F. AT WHICH TEMPERATURE MORE OF THE PROPANE IN THE LIQUID IS VAPORIZED, FLOWING RESIDUE LIQUID AND VAPOR FROM SAID OTHER HEATING ZONE INTO A LOWER PART OF THE DISTILLING ZONE, SUPERHEATING SAID VAPOR IN THE DISTILLING ZONE BY SPRAYING A PORTION OF SAID RESIDUE LIQUID HEATED TO SUBSTANTIALLY 320* F. INTO CONTACT AND DIRECT HEAT EXCHANGE RELATIONSHIP WITH SAID VAPOR IN AN UPPER PART OF THE DISTILLING ZONE TO CAUSE SUPPRESSION OF FOAMING IN THE LATTER, AND WITHDRAWING VAPOR FROM THE DISTILLING ZONE AFTER SAID VAPOR HAS PASSED IN HEAT EXCHANGE RELATIONSHIP WITH THE RESIDUE LIQUID. 